1. Field of the Invention
This invention relates to switchgear assemblies which house electric power switches such as circuit breakers, transfer switches and the like. More particularly, it relates to such switchgear assemblies in which the power switch is connected to the power buses in the switchgear cabinet by fixed connections.
2. Background Information
Switchgear assemblies include power switches, such as circuit breakers, transfer switches and the like, housed in metal cabinets together with sections of power buses between which the switches can be connected. In low voltage switchgear, that is 600 volts or lower, the power switches may be either draw-out mounted of fixed mounted in the metal cabinets. Draw-out mounted power switches are provided with quick disconnects on a rear face so that the power switches are automatically connected to the power buses as the switches are inserted into the cabinet from the front and automatically disconnected as they are withdrawn. Some users prefer or require that the power switches be fixed mounted, that is, secured to the power buses by fixed connections such as bolts, for instance.
In existing switchgear, there are few similarities in the assemblies and methods by which these differing constructions are mounted. The desirable goal of accommodating the same breaker arrangements despite mounting methods has for the most part not been achieved, and therefore, has historically led to different design concepts for each.
Present construction methods for fixed mounting power switches involve mounting the power switch on a bare frame or chassis utilizing holes provided in the molded power switch housing. Side accessibility is required to effect this mounting technique as well as to make the connections with the buses. As completed switchgear assemblies typically have a number of switchgear cabinets or sections arranged side by side, the side accessibility needed mandates that the power switches be installed and connected to the power buses before the units are joined side by side. This also makes it difficult to change or replace a fixed mounted power switch after the vertical sections are coupled together. The methods for changing these power switches in the field are quite involved due to the accessibility required for making the primary bus and housing connections.
There is a need, therefore, for an improved method and arrangement for fixed mounting power switches and switchgear assemblies.
More particularly, there is a need for such an improved method and apparatus which does not require side access to the vertical sections or cabinets of the switchgear assembly, so that the power switches do not necessarily have to be installed before coupling of the vertical sections.
There is a further need for such an improved method and apparatus in which the power switches can be easily removed and replaced in the field.
There is also a need for such an improved apparatus and method which also permits the power switches to be arranged in the cabinets similarly to the draw-out power switches.